Home automation systems are used to control the behavior of an environment such as a home or office building. Currently, home automation systems require a central controller to create and launch “scenes,” also called house scenes, involving multiple controlled devices. A scene is a collection of devices, such as lighting, heating and air conditioning, landscape sprinklers, window treatments, audio/visual equipment, water heaters, humidifiers, etc., set in a specific state. For example, through the use of a central controller, a user could create a scene where certain lights are set at specified levels, where the thermostat is set at a specified level, and where a stereo unit is activated and set to a particular station. This setting of devices constitutes a scene, and may be triggered by a trigger event also defined by the user, such as the press of a button on a remote control.
In automation systems using a central controller, a scene is launched, or triggered, when the central controller detects the trigger event. In response to detecting the trigger event, the central controller sends messages to the devices that are members of the scene directing them to go to their scene state. Because all messages go through the central controller, the central controller creates a single point of failure. If the central controller fails, then scenes can no longer be triggered because the controller can no longer send the necessary messages to the scene member devices to produce the scenes. In effect, if the central controller fails, the entire home automation system is rendered unusable. This single point of failure is highly undesirable to users of such systems.
Additionally, the use of a central controller creates a heavy load of network traffic. Since the central controller must send a message to each scene member device individually, the message traffic on the communication network for a scene with many member devices grows proportionally with the number of devices. For a scene with a large number of devices, this also causes a time delay time between the start of the scene when the first device gets its message until the last device gets its message. Such heavy network traffic and delay in triggering scene member devices is also undesirable to users of home automation systems.
Therefore, in light of the above, there is a need for a home automation system that provides distributed control of the system, thereby eliminating the single point of failure found in previous home automation systems. There is also a need for a home automation system that utilizes minimal scene production message traffic, thereby reducing the delay found in previous systems between the time a trigger event is received and when the last scene member is activated.